Algae cultivation has garnered much interest due to the wide variety of potential downstream products including food, fertilizer, bioplastics, dyes and colorants, chemical feedstock, pharmaceuticals, and biofuels. Additionally, algae cultivation has applications for pollution control.
Open pond systems are one system used for algae cultivation. The open pond system, however, exposes the algal crop to many relatively uncontrolled environmental factors, such as an increased risk of infestation by biological contaminants, including grazers. Grazers can be carried into open algal cultures by runoff water and windblown debris. Once in the algal solution, Grazers can multiply and consume the algal crop, sometimes ruining the entire culture.
Microscreens, zooplanktivorious fish, and pH/temperature shock methods have all been employed to combat grazer infestation in open ponds. Each of these methods has limitations. Screens have been found to be ineffective in removing the grazers, zooplanktivorious fish require food and would possibly compromise optimal growth conditions, and shocking cultures by regularly lowering or increasing pH or temperature for a short period requires large amount of chemicals or potentially expensive specialty apparatuses:
Methoprene is a relatively safe biocide. Methoprene rapidly degrades in sunlight and is practically non-toxic to humans or algae. The EPA does not consider methoprene application to result in unreasonable adverse effects on the environment.